Which type of anesthesia involves the complete loss of sensation and consciousness?

The correct choice is general anesthesia because it encompasses both a complete loss of sensation and a total lack of consciousness. This type of anesthesia is administered to ensure that a patient is entirely unaware of their environment and does not experience pain or discomfort during surgical procedures. General anesthesia typically employs a combination of intravenous agents and inhalational anesthetics to achieve its effects, which include amnesia, analgesia, and muscle relaxation.

In contrast, local anesthesia targets a specific area of the body to block sensation in that localized region without affecting consciousness; it is used for minor procedures. Regional anesthesia also affects a larger area by blocking sensation in a group of nerves, but it does not induce unconsciousness. Sedation can reduce anxiety and provides some level of pain relief, but it does not equate to the complete loss of consciousness and sensation that general anesthesia delivers. Thus, general anesthesia is the only choice that fully meets the criteria of complete loss of both sensation and consciousness.